fix: use timezone-naive UTC for created_at to avoid pgsql dataerror

db/models.py

@@ -8,7 +8,7 @@ class User(Base):
     __tablename__ = "users"
 
     chat_id = Column(BigInteger, primary_key=True, index=True)
-    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
+    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc).replace(tzinfo=None))
 
     subscriptions = relationship("Subscription", back_populates="user", cascade="all, delete-orphan")
     thresholds = relationship("Threshold", back_populates="user", cascade="all, delete-orphan")
@@ -22,7 +22,7 @@ class Subscription(Base):
     target_currency = Column(String(3), nullable=False)
     # Frequency could be 'daily', 'hourly'
     frequency = Column(String(20), default="daily")
-    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
+    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc).replace(tzinfo=None))
 
     user = relationship("User", back_populates="subscriptions")
 
@@ -36,6 +36,6 @@ class Threshold(Base):
     condition = Column(String(5), nullable=False) # e.g., '<', '>', '<=', '>='
     target_value = Column(Float, nullable=False)
     is_active = Column(Boolean, default=True)
-    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc))
+    created_at = Column(DateTime, default=lambda: datetime.now(timezone.utc).replace(tzinfo=None))
 
     user = relationship("User", back_populates="thresholds")